Extension-ladder hook.



P. H. MOULTON. EXTENSION LADDER HOOK. APPLICATION FILED MAR. 23, 1911.

1,045,165, Patented Nov. 26, 1912.

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' strength to meet the strains to which it is I s'rn'rs ATEEXTENSION-LADDER HOOK.

Specification of Letters Patent.

Patented Nov. as, rare.

Application filed March 23, 1911. Serial No. 616,311.

To all whom it may concern:

Be it known that I, FRED H. MoULToN, a citizen of the United States,residing at Lexington, county of Middlesex, Commonwealth ofMassachusetts, have invented certain new and useful Improvements inExtension- Ladder Hooks, of which the following is a specification.

This invention relates to hooks for extension ladders and similardevices. In the construction of hooks for this purpose it is greatlydesired to have a construction which will afford an effectual andpositive engagement in the downward bearing of the ladder when ingripping relation and a correspond ing freedom from engagement duringthe retraction of the upper section of the ladder while it is beinglowered, as well as a great subjected.

In discussing my present invention I shall refer to it particularly inconnection with extension ladder usage, as this best illustrates theprinciples of the invention. In such an instance it is particularlydesired that the catches ride freely over the rounds as the uppersection of the ladder is run up, but, that they be adapted to positivelycatch on any round when the upper section of the ladder is sufiicientlyextended and that they be capable of accurate centering on that portionof any round with which they find engagement. It is furthermore desiredthat upon the release of the catch the upper section of the ladder maybe run down freely without liability of the hooks again engaging. Iaccomplish this result by a certain construction and arrangement ofhooks and in the combination of the same with a pivoted latch adapted tocooperate therewith in the downward movement.

The construction and operation of this device will be more fullydescribed in the specification which follows. In the drawings which forma part of that specification I have shown as an illustrative embodiment.a form of device which I have found well adapted to practical use inextension ladder construction.

Throughout specification and drawings like reference numerals areemployed to indicate corresponding parts and in the drawings :Figure 1is a sectional view of a portion of an extension ladder showing one ofthe side hooks in engagement with a round, Fig. 2 is a similar viewshowing the hook in retracting position, and Fig. 3 is a section on theline 33, Fig. 1.

The usual extension ladder consists of two or more simple laddersslidably mounted together. In the drawings I have merely indicated thelower end of the upper section of the ladder and the upper end of thenext ilower ladder.

The side pieces 1 of the upper section of the ladder are slidablymounted on the side Epieces 2 of the lower ladder, in any suitable way,as by the straps indicated in Fig. 1. On the inner faces of the sides 1of the upfper section of the ladder I locate my hook or catch. Thisconsists of a plate 4 which is attached by screws 5 to the ladder sides1 and a cover 18 which rests upon the surrounding flange of the plate 4to protect the parts of the hook and return them in place. On the plate4: I form an integral tubular stud or extension which has an opening fora bolt 6. There is a corresponding opening formed in the face of theplate at 8, so that the bolt 6 may be passed through the plate 18,through the tubular stud 10 upon which the shank 7 of the hook 8 ispivoted, and through the side 1 of the upper section of the ladder. Thisnot only holds the plate 18 in place but affords a strong and sure'pivot for the hook, so that even if the stud 18 should wear away orbreak off the ladder could not collapse and the hook would still be heldby the bolt 6.

Upon the upper end of the shank 7, and above the hook 8, is formed a camshaped ear 9 which is adapted to strike against the rounds 3 of thelower ladder to throw back the hook 8 during the raising of the uppersection of the ladder 1.

The hook 8 is normally thrown forward in the position shown in Fig. 1 bya spring 16 coiled at its middle about a pin 17 set on the plate 4 andhaving its rear end confined by the flange of the plate 4.

The shank 7 of the hook is slotted about midway of its length, andwithin the slot is pivoted the reduced end 13 of a latch 14. This latchis of suflicient length so that when it is thrown upward it will coverthe tip of thepoint 8. On the opposite side of the pivot 12 of the latchthe end of the latch is rounded, as at 15, in the form of a double cam.This cam is grooved to guide the end of the spring 16 which bears uponit. The spring 16, therefore, normally holds the latch 14 atsubstantially right angles to the shank 7.

The flange 19 of the base plate 4 which extends part way up the inneredge of the plate is so proportioned and looked as to afford a stop forthe pivoted shank 7. The arrangement of this flanged stop is such thatthe hook 8 is allowed to be advanced so that it will stand normallyslightly beyond the flange center of the rounds 3. This is for thereason that the rounds 3 in the ordinary commercial ladder will not beabsolutely uniformly made, due to slight inaccuracies in turning and inpositioning, or, to occasional subsequent warping.

It is very desirable that the hook 7 should be capable of centeringitself on each end of any one of the rounds, so that the hook willsecure a full and complete bearing upon the round. For this reason Iprovide for a normal forward positioning of the hook 8 in the directionopposite to its line of retreat under the action of the cam ear 9. Itwill be seen by reference to Figs. 1 and 2 that the end of the spring 16not only actuates the latch 14 but also the shank 7 of the hook.

The operation of my device is as follows: Suppose that the hook be inengagement, as shown in Fig. 1, and it be desired to still further raisethe upper section of the ladder 1. If the upper section of the ladder 1be pushed up the hook 8 will be raised from the round 3 and the latch 14will be brought against this round. As the latch is freely pivoted,however, it will yield, forcing back if necessary the lever 7 to securea complete disengagement wit-h the round 3. After the round 3 is passed,if there should be another round above it with which engagement isdesired, a continued raising would bring the ear 9 against said nextround. On account of the cam shape of the ear 9 the hook would be forcedback until the point 8 of the hook cleared the top of the round, whenthe spring 16 would throw it forward to complete the hooking movementand full engagement would be made by letting the upper section of theladder settle in place. If after the latch 14 had passed the round 3 itwere desired toretract the upper section of the ladder 1, the downwardmotion would be started until the parts reached the position 16 topermit the hook to pass the round. In

this way I am able to provide for the free handling of the upper sectionof the ladder with a certainty of booking enga ement when the ladder isrun up and a certainty of V clearance of the hooks when the ladder isbeing run down. As pointed out, if the stud 10 should become worn away,or, if through any flaw or excess strain it should be broken, theengagement of the ladders would still be maintained without danger ofprecipitating the user of the ladder to the ground.

Various modifications in the construction and arrangement of the partsof my device may obviously be made without departing from the spirit ofm invention if within the limits of the appended claims.

WVhat I, therefore, claim and desire to secure by Letters Patent is:

1. A ladder lock comprising a casing, an integral round-engaging hookand shank pivoted at one end of said shank in said casing, and having anupwardly disposed cam portion adapted to contact directly with a ladderround in one direction to push the hook back from its round engagingposition, the shank on said hook having a longitudinal slot between itsends, a hook covering latch pivoted in said slot and adapted to overlapthe point of said hook, a double cam bearing on the end of said latchsymmetrically disposed with regard to said pivot and exposed on the rearside of said shank in said slot, a spring supported in said casingbehind said shank and operatively connecting with said cam bearing andsaid latch, and effective to yieldingly maintain said latch at rightangles to said hook shank and to yieldingly support said hook in roundengaging position. Y

2. In an extension ladder a pair of relatively movable ladder sections,an integral round-engaging hook and shank pivotally mounted on onesection and havingan up-:

wardly disposed cam portion adapted to contact directly with a ladderround in one direction to push the hook back from its yieidinglymaintaining said pivoted latch at 10 round engaging position, a hookcovering substantially right angles to said shank.

latch pivoted to said shank and carried In testimony whereof, I afiix mysignature thereby and effective to cover the point of in presence of twowitnesses.

said hook to receive the direct thrust of a ladder round from the otherdirection to FRED MOULTON' push the hook from round engaging posi-Witnesses:

tion, and a spring yieldingly supporting M. SUMNER CocoAN,

said hook in round engaging position and ELLIs SPEAK, Jr.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

